In general, in order to generate voice, head sections of a plurality of predetermined voice information are successively reproduced, and address control and access to a memory are performed through a control circuit.
For example, such a device is disclosed in Japanese Publication for Unexamined Patent Application No. (Tokukaihei) 6-325587. In an information reproducing apparatus disclosed in the above publication, a plurality of voice data are recorded in a memory and operation-start positional information of each voice data is recorded in an index section. Moreover, a main control circuit controls an address control circuit to read out the operation-start positional information and specific positional information of each voice phrase from the memory. Thereafter, the contents of recording recorded in a position between the respective positional information are reproduced successively with respect to each voice data. Namely, in this structure, each phrase is selected by the main control circuit instead of allocating voice data to be written or setting a voice start address.
Therefore, it is necessary for the main control circuit to observe the entire operations from the start of voice generation until the voice generation is stopped, resulting in a complicated and expensive circuit. In addition, in this structure, it is impossible to directly start or stop the voice generation by directly specifying a voice start address through a peripheral or an external CPU (central processing unit). Moreover, it is difficult to add new voice data to the memory, or reproduce voice from the middle of a phrase by a simple control.
One example of the integrated structure where the voice generation function is included in the microcomputer is a voice generation chip. The voice generation chip reproduces voice by turning on a port determined every other phrase. This structure is advantageous in terms of cost. However, it is also difficult to start the voice generation from the middle of a phrase, or continuously reproduce more than one phrase in a smooth manner.
Moreover, it is impossible to perform fine and stable control with a simple system having a small number of ports if the voice generation function is independent of the main CPU. Additionally, the start and stop of the voice generation cannot be smoothly controlled through the external CPU and other devices. It is thus difficult to continuously generate voice from different phrases, and continuously generate voice during reproduction of another voice. Here, the structure in which the voice generation function is independent of the main CPU refers a structure in which the voice generation function is used as an internal peripheral circuit formed as a single chip, or a structure in which the voice generation function is used as a voice generation device.
Regarding a method of stopping the generation of voice, one method records a code representing the data length of voice data in advance, and detects a time at which the voice generation stops by reading out the code at the start of the voice data. In this case, a down counter or an address comparator is separately required to judge whether an address containing voice stop data is accessed before a voice address pointer reaches the final address of the data. When a judgment is made using the down counter, since it is necessary to decode the number of steps of voice data to be reproduced from a code representing the number of voice steps in the voice data into the form of the down counter, a decoder for detecting the count of the step number is further required.
In order to avoid the use of the down counter and the decoder for the step number counter, the following method may be employed. In this method, a one-bit flag is allocated for each step, and the generation of voice is stopped when the control circuit reads out the flag. In this case, although the circuit structure is simplified, a memory having a bit capacity corresponding to the addresses of voice data is separately required, resulting in an increase in the cost.